From time immemorial, people have cooked their food. It is reasonable to speculate that the earliest cooked food was meat cooked over an open campfire. For most of human history, the predominant way of cooking food is to suspend the food over a wood-fueled fire. As technology and civilization have advanced, other means of cooking food have been devised. Within the last century, electric ranges and ovens or gas fired ranges and ovens have been the preferred way of cooking food in affluent countries like the United States.
However, to some people, food cooked in this conventional manner lacks the savoriness of food cooked over an open flame. This has led to an atavistic cooking ritual, especially common in suburban areas, known as barbecuing. In barbecuing the cook attempts to achieve something of the particular flavors that result from cooking food over an open wood flame without the inconvenience and trouble of actually cooking it in that fashion. Although within the last third of the century much has changed in the role of men and women in industrialized countries, it may still be stated that cooking inside on the conventional range is primarily the province of women while cooking outside or barbecuing is primarily the province of men. Because this type of cooking is more of a social occasion than a required necessity, many men take pride in their skill as a "barbecue" cook. Hence, elaborate machinery is used to barbecue to make it as convenient, simple, and as fool proof as possible.
Perhaps the simplest type of barbecue apparatus is simply a fire pan with a grill suspended above it. Combustible materials are placed in the fire pan and are ignited. When the combustible materials are considered to be at an appropriate state,food, usually pork, beef, or chicken, are placed on the grill above the fire pan where the food is cooked both by radiant and convective heat. Typically, manufactured charcoal briquettes are used as the source of heat. As the meat begins to cook, rendered fat or other juices will drip off the meat onto the charcoal briquettes, sizzling and smoking. The type of briquettes employed may also contribute to the flavor of the smoke so generated. Hickory or mesquite are usually viewed as the preferred flavors, hence, hickory or mesquite briquettes are the ones most commonly found in the market. The smoke rises to mingle with the meat and impart, to some degree, a smokey flavor to the meat. Almost all supermarkets or variety stores will sell one or more grills of this type, as well as the supplies necessary for cooking on this type of grill. This is probably the preferred form for people who only occasionally cook in this fashion.
However, within the last fifteen or twenty years more elaborate barbecue equipment using gas as a heat source has become very common. Some of these gas fired grills that are connected directly to a gas source, like the natural gas lines that may be used for heating and cooking within a home. Because many areas do not have readily available natural gas supplies, portable tanks filled with a liquified gas can be used instead of a natural gas line. These tanks are usually filled with propane, hence, called "propane tanks". The smallest and least elaborate of these gas grills may sell for under $100.00. However, there are some gas grills designed for permanent installation that may cost many thousands of dollars.
These type of grills are relatively standard in design, although variations within this design are common. Ordinarily, the cooking unit itself is a relatively oblong enclosure that is split approximately in half with the upper half being hinged so that it can be opened. Centered in the enclosure is a grill or grid for support of the food. Below the enclosure is some type of heat distributing device. This device may be lava rocks, metal briquettes, grease collection pans, or other designs. A great deal of ingenuity has been expended in designing this particular feature of the grill. It is important in the functioning of the grill because the heat must be distributed evenly during the cooking process and this heat diffusion device also receives the rendered fat or other cooking juices from the meats being cooked so as to appropriately sizzle and smoke to impart the necessary flavors to the meats being cooked. Below this heat diffusion device is the heat source. Although there are electrical powered grills, the most common grill designs use a burner for a combustible gas--either natural gas or propane. In a grill that uses hickory or mesquite briquettes as the heat source, there is no heat diffusion device. However, the briquettes must be ignited and they must burn down to where the briquettes are largely covered with white ash before the temperature in the grill for cooking is viewed as appropriate. This process, depending on the type of briquettes, can take a substantial amount of time. One of the advantages of the gas fired grill is that the gas may be ignited immediately which heats the intervening heat diffusion device much quicker to the desired temperature so that cooking can begin shortly after the gas is ignited, rather than waiting for the briquettes to "age".
The conventionally designed gas grills as outlined above are not ordinarily equipped for cooking by "smoking". Certain types of food, especially fish or large types of food, such as hams or turkeys, cannot be cooked over high heat. To do so is impractical because the outside of large meat items like the ham or turkey will be scorched well before the inside is cooked. Fish, if cooked over a high heat, dries out quickly. Consequently, it is desirable to cook these types of foods over a very low heat. The heat may be too low for the natural juices to ignite and smoke, hence, it is necessary to add something to produce the smoke necessary to impart the desirable smoking flavor in the meat. There are dedicated cookers designed to cook food for a prolonged period over low heat using smoke to impart flavor. These cookers are usually called "smokers". One design of a smoker is seen in the Pfund U.S. Pat. No. 2,789,877. In this design there is an enclosed cooking space with a vented chimney at the top of the cooking space. Several grids are suspended within the cooking space on which food to be smoked will be placed. At the bottom of the cooking space is an electric heat plate. A pie pan or similar container is placed on top of the heat plate. The pie pan contains a piece of wood, wood chips, or sawdust. The heat plate is turned on, which will begin to char the wood, filling the enclosed space with smoke. Additionally, the electric heat plate can be adjusted to achieve a satisfactory cooking temperature--high enough to slowly cook the food, but low enough not to quickly overcook it before the smoke within the heated space can penetrate the food and impart the desired smokey flavor. However, for most people who will only wish to smoke food on a rare basis, the purchase of a dedicated smoker is not practical. To that end, a variety of expedients have been devised so that a regular barbecue cooking apparatus can be modified for use as a smoker. For example, the Tygart U.S. Pat. No. 1,964,379 discloses a device to be used as part of gas fired barbecue ovens. Here, there is a conventional gas fired barbecue oven. Below that oven is a separate container with a separate burner. Wood chips, sawdust, or a log will be placed in the separate container and heated by the separate burner. A flue controlled chimney will allow smoke to enter the regular barbecue oven to mingle with the food there. Another approach is seen in Haskins U.S. Pat. No. 4,869,163. This is a smoking unit designed to be used inside a conventional gas grill. The smoking unit is a self-contained enclosed unit. At the bottom of the smoking unit are containers for wood chips or other smoke producing materials. Above that is a vented pan leading to a grill on which food would be suspended. The Haskins smoking unit would be suspended over the ordinary gas fired burners with appropriate wood chips or other combustible materials contained within the smoking unit. Food would be fixed on the grill and the entire unit closed. The gas burner would be ignited which would then heat the combustible materials producing the appropriate smoke. Because the entire unit is enclosed, it is easier to regulate the heat within the unit to an appropriate level that is hot enough to cook the food by smoking, but not too hot to cook it before sufficient time is allowed for the smoke flavors to intermingle into the food and give it the requisite desired smokey flavor. Other gas fired grills have a tray suspended between the gas burners and the permanent heat diffusion device. The tray may be slid out and sawdust, wood chips, or even commercially available liquid smoke may be loaded into the tray, the tray returned to the body of the cooker, and then the burners ignited to begin charring the combustible products within the tray to provide the requisite smoke to impart the desired smokey flavor to the food being cooked. However, each of the above designs leave something to be desired in terms of convenience of use and practicality. To that end, there is room for an improved gas burner design that permits a standard gas grill to be used as a smoker.